1. Field of the Invention
The present invention relates to methods and an apparatus for detecting an abnormal state of a rotating electrical machine, and in particular relates to methods and an apparatus for detecting an abnormal state of a rotating electrical machine by performing current signal analysis.
2. Description of the Related Art
The components of a rotating electrical machine (including generators and motors) may develop defects due to various reasons such as aging or external factors. The defects may not immediately influence the general operation of the rotating electrical machine, but, if not inspected and replaced, the rotating electrical machine may finally break down, thus increasing maintenance cost or destroying of the rotating electrical machine.
Conventionally, the rotating electrical machine is periodically inspected and maintained to reduce the probability for damage caused by the rotating electrical machine breaking down, which is troublesome. Sometimes, shock sensors and temperatures sensors are used in the prior art to monitor rotating electrical machines for abnormal shocks or temperatures. However, additional measuring instruments are required, such as an accelerometer. The additional measuring instruments not only increase manufacturing cost but may also malfunction due to demagnetizetion, displacement or ageing.
Therefore, a lost cost method and apparatus which can easily detect an abnormal state of a rotating electrical machine and provide an early warning for possible malfunction of the rotating electrical machine is needed.